Quote:
Originally Posted by bertoni
Well, that depends on what you mean...  The stated goal is to export phosphorus and nitrogen from the system by consuming them from the water column, and then out of the tank via the skimmer. That process could be accomplished by growing a fairly steady bacteria population that exports nutrients via skimming byproduct and the inevitable death and replacement rate, at least in theory. So a net increase of bacterial mass might not be required. Given that some people report dosing carbon for years, it's fairly clear to me that the tank reaches a relative steady state, possibly fairly quickly. Of course, export by skimming the bacteria themselves probably happens to at least some extent. I don't know of anyone who has surveyed the change in bacterial levels in the skimmate with carbon dosing, not over a long time frame, anyway. |
This seems like a reasonable high level description. I wonder if what you are feeding by carbon dosing takes over ammonia capture and export from the ammonia oxidizers-denitrifying system.
I would wager that the steady state that you posit above is reached when the ratio of carbon added to the food nitrogen added is at the correct ratio to favor near complete assimilation with little or no waste ammonia to be oxidized to nitrate. This is Belgian Anthias’ point. And when there is a reduced amount of nitrate, then maybe the denitrifying bacteria population is decreased, another Belgian Anthias point.
I have a fish only system with a lot of macro algae but periodic outbreaks of unsightly things (diatoms, cyanobacteria, dinoflagellates all ID’d under a microscope) BUT phosphates are usually undetectable and nitrates less than 0.5 ppm except for occassional unexplained short term nitrate spikes. PO4 and NO3 are poor perdictors of nuissance organism growth. So, I am wondering now based on this debate whether shifts in ammonia production-consumption might be a useful predictor, though impossible for me to measure. I might just try carbon dosing based of nitrogen input to see if the periodic nuissance growth goes away.
Dan